Pulsed proton NMR will be used to measure molecular dynamics in liquid crystals and in model membranes. Pulsed gradient NMR techniques used previously in this lab to measure lipid lateral diffusion in model membrane lecithin/water multilayers will be used to measure the effect of ions (Ca +2), alcohols, and drugs on the diffusion. Diffusion in mixtures of lipids will be studied with special emphasis on the effects of lateral phase separations. NMR proton relaxation (longitudinal and rotating frame) and proton linewidth studies will be used to study the phase behavior of octaphenylcyclotetrasiloxane, a compound suspected of being a liquid crystal or a plastic crystal. Carbon-13 NMR and proton enhanced carbon-13 NMR will be applied to mixed lipid systems to provide information on conformational changes accompanying lateral phase separations. Deuterium NMR will be used to study dynamics in membranes, in cells, and in alkanes dissolved in model membranes.